if we remove all of earth's seas and oceans it would no longer be a sphere,since the water all over covers it ,it appears a sphere,right?

The oceans are a mere 2 miles deep on average. On a sphere 7800 miles in diameter, that's chump change. The highest mountains and deepest oceans are proportionately no thicker than the skin is on an apple.

Note though, that Earth is not a perfect sphere. It is an oblate spheroid, thicker around its equator than around its poles by about 60km, due to its rotation.